Final answer:
Ligand-gated channels are found mostly in the nervous system, particularly at synapses where the transmission of nerve impulses occurs. They play a crucial role in initiating the propagation of electrical signals in neurons. These channels are also present in other tissues and organs, such as the heart, where they regulate the flow of ions and contribute to muscle contraction.
Step-by-step explanation:
A ligand-gated channel is a type of ion channel that opens when a specific signaling molecule, known as a ligand, binds to the channel protein. In the case of ligand-gated ion channels, the ligand is usually a neurotransmitter. When the ligand binds to the extracellular region of the channel, it causes a conformational change in the protein's structure, allowing ions like sodium, calcium, and potassium to pass through the channel.
Ligand-gated channels function most commonly in the nervous system, particularly at synapses where the transmission of nerve impulses occurs. These channels play a crucial role in initiating the propagation of electrical signals in neurons. They are also found in other tissues and organs, such as the heart, where they regulate the flow of ions and contribute to muscle contraction.